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Re: [Qemu-devel] mipsIV support for mips-linux-user
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] mipsIV support for mips-linux-user |
Date: |
Thu, 9 Apr 2009 00:17:24 +0200 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Mon, Mar 30, 2009 at 01:29:29PM -0400, Vince Weaver wrote:
> On Mon, 30 Mar 2009, Aurelien Jarno wrote:
>
>> Do you have the end of qemu.log when running your code with -d in_asm,op?
>
> The first cop1x instruction happens relatively deep into the program, so
> the debugging dump is pretty larege. How far back do you want?
>
> It looks like no matter what cpu option I pick, the HFLAGS is set to
> 0x0022 (which is only the usermode and FPU flags).
>
> Because of this the generated assembly in the debug output
> unconditionally generates an illegal instruction exception the first time
> a cop1x instruction is executed (in my case, "msub.d")
This instruction is clearly marked as MIPS64 only in the manual.
> I've been digging through the qemu mips code, and I can't seem to find
> where the hflags are set in the usermode case.
>
> The only place that sets the MIPS_HFLAG_COP1X is in exec.h,
> "compute_hflags()" but that doesn't ever seem to be called if
> CONFIG_USER_ONLY
I think this should be enabled in cpu_reset(), where env->hflags is
setup for user mode.
But I am actually concern about the results you get when enabling
MIPS_HFLAG_COP1X. If your program is expecting to have the FPU in 64-bit
mode you may have really strange results. Did you check them?
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
- Re: [Qemu-devel] mipsIV support for mips-linux-user,
Aurelien Jarno <=